Aquarium cover



FIG. 1 is a front elevational view of an aquarium cover showing my new design;

FIG. 2 is a left side elevational view thereof, the right side being a mirror image of the side shown;

FIG. 3 is a top plan view thereof; and

FIG. 4 is a rear elevational view thereof. 

The ornamental design for a aquarium cover, as shown and described. 